The goal of this proposal is to utilize a variety of spatial memory tasks to examine the functional role of the hippocampus (HPC) in spatial memory. Each of these tasks is a human analogue version of tasks that have been extensively developed and demonstrated to be sensitive to HPC damage in nonhumans. The fMRI group at Yale has recently developed an fMRI methodology that allows for precise detection of functional activity changes in the HPC; a structure that, before this development, has been extremely difficult to image due to its proximity to bone and sinuses which cause signal loss and spatial distortions. In addition, it is an aim of these studies to examine whether the observed changes in HPC activity correlate with spatial performance in these tasks. Both neurologically normal participants and patients with epilepsy will be tested. The neurologically normal participants will provide a control group for comparing with the patients as well as providing a group for piloting additional spatial memory tasks. By examining the functional role of the HPC in patients both before unilateral HPC resection and afterwards, a better understanding of HPC functioning can be obtained. Moreover, this information may be essential in guiding the neurosurgery so as to maximize the benefits of the surgery while minimizing the amount of critical tissue that is removed.